Recording elements in which information is recorded by thermally deforming an optical recording layer are known. Such elements are useful in rapidly recording large amounts of digital information in a small area. These elements are also useful in recording video information.
Recording on an optical recording element is accomplished by an information modulated beam of high energy-density radiation such as a laser beam. The laser beam is focused onto the surface of the optical recording layer of the element. The recording layer absorbs energy from the laser so that a small portion of the layer is deformed thereby forming an information bearing record element. The deformations may be in the form of pits, holes or other changes in the material. This technique of optical recording on a heat-deformable recording layer is usually referred to in the optical recording art as "ablative recording".
Generally, there is continuous relative motion between the laser beam and the layer so that as the layer is pulse modulated, discrete deformations of varying sizes are created in the layer. The sizes and spacing of these deformations constitute the encoded information. A variety of materials has been proposed for use for the heat-deformable recording layer.
It is known to overcoat heat-deformable optical recording layers for a variety of purposes. For example, during the ablative recording process, a portion of the optical recording layer is removed in the form of a vapor which condenses and rains back upon the recording layer creating the potential for unwanted noise. To overcome this problem, U.S. Pat. No. 4,069,487 disclosed protective overcoats. These overcoats range in thickness of from 0.15 .mu.m to 10 .mu.m.
In U.S. Ser. No. 600,643, filed Apr. 16, 1984 in the name of Gupta et al and entitled "Ceramic Overcoated Optical Recording Elements Having Heat-Deformable Recording Layers", there is disclosed a recording element comprising a support having thereon a heat-deformable optical recording layer having a transparent ceramic overcoat having a thickness up to about 0.05 .mu.m.
Useful information bearing record elements having a particularly useful heat-deformable optical recording layer comprising a dye and a binder are disclosed in U.S. Pat. No. 4,380,769 in the name of Thomas et al. This element stores the information in the form of heat deformations in information tracks. This element can be erased by applying heat uniformly over the surface to smooth out the information tracks. The problem is that the erasure cannot be carried out on such elements selectively, track by track or on portions of such tracks.